Recent development of landing dynamics over small celestial bodies

Landing exploration of small celestial bodies is currently one of the most direct, efficient, and challenging approaches to obtaining information about small bodies. It has become a hot issue in deep space exploration, with particular scientific significance for studying the origin of planets and life. Landing dynamics is the prerequisite and guarantee for successfully implementing the small body landing mission, which presents a new challenge to astrodynamics. The new challenges involve modeling the complex space perturbation environment of the small body, describing the lander and the rugged small body surfaces, and analyzing the high-dimensional nonlinear dynamical problems with uncertainties, such as the coupling orbit-attitude motion of the lander. To this end, this paper systematically reviews the existing landing exploration missions of small celestial bodies and the main problems of landing dynamics. The development status of the landing exploration robot and the micro-gravity ground experiment testbed are briefly summarized. Additionally, this paper concludes the dynamical methods exploited to analyze the free landing motion over rugged small body surfaces. The irregular gravitational field modeling method, the collision detection and analysis, the binary asteroid system’s landing dynamics, and the small bodies’ surface mechanical properties are systematically discussed, respectively. Finally, the future development of landing dynamics is prospected according to the requirements of the Chinese small celestial body exploration missions.